#include <fstream>
using namespace std;
#define N 1000002
ifstream cin("fractii.in");
ofstream cout("fractii.out");
int fi[N];
int main()
{
    int n,i,j;
    long long x=0;
    cin>>n;
    for(i=1;i<=N;i++) fi[i]=i-1;
    for(i=2;i<=n;i++){
        x=x+fi[i];
        for(j=2*i;j<=n;j=j+i) fi[j]=fi[j]-fi[i];
    }
    cout<<2*x+1;
    return 0;
}